Heat seal for fuel injection nozzles

ABSTRACT

An elongated bushing consisting of a polymer such as tetrafluoroethylene may be formed in the configuration of a sleeve. The bushing may be fit over an injection nozzle mounted within a bore formed within the cylinder head of an internal combustion engine. The bushing may be axially compressed between an internal shoulder formed within the bore of the cylinder head and a built-up portion on the nozzle assembly. The axial compression acting on the bushing causes the bushing to have radial expansion so as to completely fill the annular space formed between the nozzle and the internal wall of the bore defining a cavity within the cylinder head. An annular disk-like monel member may be fit over the nozzle and supported adjacent the hot axial end of the bushing to insulate the surface thereof against the effect of hot cylinder gases.

United States Patent [151 3,695,235

Anderson 45 Oct. 3, 1972 HEAT SEAL FOR FUEL INJECTION OTHER PUBLICATIONS NOZZLES Diesel Equipment Superintendent, Sept. 64, p. 40. [72] Inventor: Harold E. Anderson, Redondo Beach, Calif. Primary ExaminerLaurence M. Goodridge Assistant Examiner-Cort Flint [73] Asslgnee' cnrpomfion L08 Attomey--Burns, Doane, Swecker&Mathis [22] Filed: Aug. 26,1970 [57] ABSTRACT [211 App]. No.: 67,081 An elongated bushing consisting of a polymer such as tetrafluoroethylene may be formed in the configuration of a sleeve. The bushing may be fit over an injec- "123/32 123/32 tion nozzle mounted within a bore formed within the [58] Field 239/86 92 cylinder head of an internal combustion engine. The

[102412 114 bushing may be axially compressed between an internal shoulder formed within the bore of the cylinder head and abuilt-up portion on the nozzle assembly. [56] References cued The axial compression acting on the bushingcauses UNITED A E PATENTS the bushing to have radial expansion so as to completely till the annular space formed between the 2,058,487 10/ 1936 MOFk ..123/32H nozzle and the internal wall of the bore fi i a 3,056,577 10/1962 KUllSelS ..239/DIG. 19 cavity within the cylinder head. An annular disk like 3,131,866 5/1964 Cummms et al ..239/533 monel member may be fit over the nozzle and 2,897,800 8/1959 Haas ..123/32 V ported adjacent the hot axial end f the bushing to g fz 2 332 3 sulate the surface thereof against the effect of hot O a d 3,058,452 10/1962 Espenschied ..123/32 R Cy m er gases 3,038,456 6/1962 Dreisin ..123/32 R 7 Claims, 4 Drawing Figures HEAT SEAL FOR FUEL INJECTION NOZZLES BACKGROUND OF THE INVENTION The present invention relates generally to fuel injection nozzles for internal combustion engines and more particularly to an improved heat sealing apparatus and method for protecting fuel injection nozzles and associated apparatus from hot cylinder gasses.

Over the years many significant improvements have been made in the design and operation of fuel injection apparatus for both spark and compression ignition engines. Today fuel injection nozzles are compact and simple devices having a high degree of efficiency. One of the problems which has been encountered by engineers in incorporating these improved injection devices within operational internal combustion engines has been the detrimental effects of high temperature cylinder gasses acting upon the outlet end of the nozzle. Also, these gases may enter the annular space formed between the nozzle and the surrounding bore hole into the area near the inlet portion of the nozzle to cause additional heating and carbonization'problems.

In order to prevent the bypass of cylinder gases through the annular space between the nozzle and the surrounding bore hole formed within a cylinder head,

engineers have utilized annular seals or gaskets of conventional design which are sometimes disposed within annular recesses formed circumferentially about the tubular nozzle. These seals have consisted of. materials such as copper or the like and, in spite of the presence of such sealing devices, cylinder gas seepage often occurs through the annular passage between the nozzle and the surrounding bore hole. The weeping gases deposit a carbonaceous substance along the outer surface of the nozzle which deposit causes an adherence between the nozzle and the internal surface of the cylinder head bore hole. Additionally, the hot gasses acting upon the full length of the nozzle tend to impart a substantial amount of heat thereto which is then conducted through the nozzle to associated apparatus outside the combustion area of the cylinder. The carbonaceous deposits are not confined to the smooth surface of the nozzle, however, but also form on whatever connecting means may be utilized to mount the nozzle within a cylinder head bore hole. Since the removal of a fuel injection nozzle may occur quite frequently, as the removal would normally be associated with the replacement of spark plugs in a spark ignition engine, it is important that the parts for mounting the nozzle within the cylinder head bore hole not become frozen together by such cylinder gas deposits.

One approach for shielding the length of an injection nozzle against the high temperatures of the cylinder gases and for simultaneously preventing carbonaceous buildups along the surface of the nozzle is to coat the nozzle with a polymer substance before installing the nozzle within an internal combustion engine. Such a provision has been found to be less than satisfactory because there still exists an axial passage between the coated nozzle and the internal surface of the cylinder head bore so that carbonaceous gases may seep therethrough to the members of the apparatus provided for mounting the nozzle. Also it has been found that the high temperature gases acting along the relatively large surface area of such a polymer coating tends to burn the coating away which burning exposes at least a portion of the nozzle so as to render to coating ineffective to solve the heat conduction problem. Even when a gasket or a sealing device is used with such a polymer coating, is has been found that breathing will still occur so that the overall results of the composite are unsatisfactory. Therefore, freezing of fuel injection nozzle mounting apparatus and the burning of the cylindrical surface of a polymer coated on a nozzle are problems which have heretofore not been solved.

OBJECT S AND SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an improved heat seal for a fuel injection nozzle used in internal combustion engines.

It is another object of the present invention to provide a method and apparatus for preventing breathing of cylinder gases through the annular space defined by the outer. surface of a fuel injection nozzle and the inner surface of a surrounding cylinder head bore hole.

It is still another object of the present invention to provide a method and apparatus for preventing carbonaceous deposits along the length of a fuel injection nozzle.

It is yet another object of the present invention to provide a method and apparatus for preventing the freezing of mounting apparatus used for securing a fuel injection nozzle within a bore hole formed within the head of an internal combustion engine.

It is a further object of the present invention to provide a method and apparatus for reducing the conduction of heat from the interior of an operating cylinder of an internal combustion engine through a fuel injection nozzle to associated apparatus outside the combustion area of the cylinder.

It is still a further object of the present invention to provide a method and apparatus for shielding a fuel injection nozzle from high temperature cylinder gases using a sleeve-like heat seal which will not be burned away by the action of such hot cylinder gases.

It is yet a further object of the present invention to provide a method and apparatus for protecting a fuel injection nozzle from the extreme heat and pressure of cylinder gases which heat seal solves many of the problems confronting the industry today.

The foregoing objects are carried out by the provision of an elongated sleeve-like heat sealing member consisting of a polymer substance and disposed about a fuel injection nozzle. Upon the insertion of the nozzle within a bore hole formed in a cylinder head of an internal combustion engine, the sleeve member is axially compressed so as to completely fill the annular space formed between the surface of the nozzle and the internal surface of the surrounding bore hole. The sleeve member is thereby forcibly urged radially and axially against the surfaces of .both the nozzle and the bore hole. In an independent feature of the invention, an annular disk-like member may be disposed adjacent the hot end of the nozzle so as to insulate that end of the sleeve member from the effects of high temperature cylinder gases.

BRIEF DESCRIPTION OF THE DRAWINGS While the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification, a preferred embodiment is described in the following detailed description which may be best under stood when read in connection with the accompanying drawing in which:

FIG. 1 is a perspective view of a heat seal formed in accordance with the present invention:

FIG. 2 is an axial sectional view of the heat seal of the present invention operationally installed about and immediately adjacent a fuel injection nozzle disposed within a bore hole formed through a cylinder head;

FIG. 3 is an enlarged cross-sectional view of an apparatus according to the present invention installed in another injection nozzle configuration; and

FIG. 4 shows a modified heat seal disposed about a frusto-conical cooling member which, in turn, is disposed immediately adjacent a fuel injection nozzle mounted within a cylinder head of an internal combustion engine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing in which like numerals are used to indicate like parts throughout the various views thereof, FIG. 1 shows a heat seal formed in accordance with the present invention.

The seal comprises a bushing having an elongated hollow cylindrical body indicated generally as 10. The diameter of the internal surface 12 may be approximately equal to the outside diameter of a fuel injection nozzle to be protected. The outer cylindrical surface 14 of the heat seal may be approximately equal to the diameter of the internal surface of a bore hole formed in a cylinder head of an internal combustion engine which bore hole is to be utilized for retaining the fuel injection nozzle. The length of the sleeve 10 may be slightly more than the length of the surrounding cavity so the sleeve is expanded radially when assembled. The reasons for providing the aforementioned diameters and lengths so that the seal 10 fits tightly within the annular cavity between the bore and the nozzle will become apparent upon reading the remaining portion of the detailed description. The heat seal 10 may comprise a polymer substance such as tetrafluoroethylene which is cold under the trademark Teflon by E. I. du Pont de Nemours & Co., Wilmington, Delaware.

Referring now to FIG. 2, the hollow cylindrical sleeve 10 of FIG. 1 is shown in an operational posture. A bore hole is formed within a cylinder head 16 and is defined by the internal cylindrical surface 18. The axial end of the bore hole surface 18 adjacent a combustion area 20 within the cylinder 16 is formed with an internal shoulder 22. From the shoulder 22 to the combustion chamber end of the bore hole, the surface defining the bore hole may be conical as is surface 24. A fuel injection nozzle 26 is disposed within the bore hole defined by the surface 18 and is provided with the heat seal 10 fitted coaxially thereover. The fuel injection nozzle 26 may be of the conventional type wherein a fuel inlet conduit 32 connects therewith at a generally 90 angle thereto. A fuel inlet fitting 28 may be welded or threadedly engaged on the tubular nozzle 26 at a point remote from the outlet end 30 of the nozzle. The fuel inlet conduit 32 communicates with the fuel inlet fitting 28 and directs fuel thereto from a fuel supply conduit (not shown) which is connected to the fuel inlet conduit 32 by means of a second fitting 34.

The fuel inlet fitting 28 mounted on the nozzle 26 may be formed as a partial spheroid having a planar lower surface 36. A threaded bore hole 40 may be drilled within the cylinder head adjacent the fuel injection retaining bore hole defined by the surface 18 and may be sized to receive a bolt member 42. Threads 44 on the bolt member 42 matingly engage within the threads 46 formed within the bore 40. A cantilevered J- shaped clamping member 48 may be provided and formed with two holes defined by surfaces 50 and 52. The bolt 42 fits through the hole in the member 48 defined by the surface 50 and is thereafter threadedly engaged within the threads 46 formed in the bore hole 40 of the cylinder head 16. The hole in the clamping member 48 defined by surface 52 fits over a rear portion 54 of the fuel injection nozzle 26. I

A terminal end 55 of a bent portion 56 of the cantilevered clamping member 38 is caused to engage with a surface 58 formed on the cylinder head 16 in response to the tightening down of the bolt 42 within the threaded bore 40 of the cylinder head 16. The action of the cylinder head surface 58 on the terminal end portion 55 of the portion 56 of the clamping member 48, 48, causes a cantilevered portion 60 of the clamping member 48 to pivot downwardly about the bolt 42 so as to exert a downward force on the upper planar surface 38 of the fuel inlet fitting 28. This arrangement has been sometimes characterized as a saddle clamp.

The length of the heat seal 10 is such that when the axial end 62 of the heat seal is resting on the internal shoulder 22 of the cylinder head bore surface 18, the upper axial end 64 of the heat seal 10 extends somewhat above a shoulder 66 defining a portion of the varied diameter surface of the overall fuel injection nozzle retaining bore formed within the cylinder head 16. Since the heat seal 10 extends above the surface of the radially extending shoulder 66, the downwardly urged lower planar surface 36 of the fuel inlet fitting 24 compresses the heat seal 10 against the shoulder 22 formed adjacent the outlet end 30 of the nozzle 26. Of course, a conventional gasket or washer 65 may be disposed between the surfaces 64 and 66 and, in that case, the end 64 of the seal 10 should extend somewhat above the surface 67 of the gasket 65.

Referring now to FIG. 3, the heat seal of the present invention is shown in an operational posture within a fuel injector nozzle having a somewhat different configuration from that shown in FIG. 2.

A fuel injector body 11 is fit within a fuel injector housing 13 and is provided with a bore hole 15 for the mounting insertion of an alignment pin 17. A spray tip member 19 is fitted within the housing 13 and properly aligned by the'placement of the pin 17 within a bore hole 21 formed therein. A lower end 23 of the spray tip member 19 extends through a bore hole formed in the cylinder casing 16. The lower end 23 of the spray tip is formed with spray holes 25 for directing a fuel spray to the interior of the cylinder 16. A drain plug 27 may be fit within bore hole 29 of the body 11 after assembly of the overall nozzle.

A valve stem 31 is biased to normally close the spray holes 25 by a spring 33 acting on a seat portion 35 of the stem 31. When pressurized fuel enters a passageway 37, it forces the stem 31 to open the holes 25 against the bias of the spring 33 and fuel is injected into the engine cylinder 16 as a result thereof.

A heat seal 10, according to the present invention, is

disposed in the cavity 39 defined by the cylinder casing 16 and the spray tip 19. The seal is of length which is greater than the length of thecavity 39. However, the seal 10 is longitudinally compressed between a gasket 41 and an annular, monel shield 43 which is positioned at the lower end of the cavity 39, and thus longitudinally shortens the cavity 39.

The gasket 41 may be of a conventional type and may be used to prevent any gases from seeping through the space 45 defined by the juncture of members 13 and 19. The monel shield 43 protects the lower axial end 62 of the heat seal 10 against burning due to direct contact with the hot gases within the cylinder. A small annular space 47 may be provided for permitting the seal 10 to extrude if the volume of material thereof exceeds the volume of the cavity 39.

The seal 10 prevents carbonaceous substances and heat from causing the seizing of the removable parts of the nozzle assembly. Such seizing may cause, for example, the shearing of the alignment pin 17 during the removal of the nozzle for maintenance.

Since the area of the radially extending' surface of the axial end 62 of the heat seal 10 is relatively small, the burning effect thereof may be considered negligible and, hence, the monel annular insulating member may be considered to be optional. However, the monel be retained within a cylinderhead bore, defined by the surface 18, by a saddle clamp apparatus similar to that shown in FIG. 2 or by any suitable means. A cooling muff 72, comprising a generally frusto-conical shape with an internal axial bore formed therethrough defined by a surface 74, may be fit over the fuel injection nozzle 26 for enhancing the cooling thereof. Fins 76 may be formed on the cooling muff 72 and an internally stepped up portion 78 of the overall bore may be formed to extend axially of the cooling muff 72 to accommodate the retention of the fuel inlet fitting 28. A radially extending surface 80 of the stepped up portion 78 of the overall internal bore of the cooling muff 72 engages with the lower planar surface 36 of the fuel inlet fitting 28. When an axial force is applied to the upper planar surface 38 of the fuel inlet fitting 28, which force is then transmitted to the cooling muff 72 by the action of surface 36 of the fitting 28 on the radially extending surface 80 of the cooling muff, the frusto-conical shaped heat seal 70 is generally axially and radially compressed within the cylinder head bore hole. As can be seen in FIG. 4, the seal 70 expands outwardly in the axial direction to fill the entire surrounding cavity. The seal 70 thus provides a gas barrier which extends axially and radially of the portion of the annular space (between the cooling muff 72 and the bore hole) lying in a radial plane defining the lowermost limit of the annular space. By this configuration, once again, a barrier is provided which extends transversely of hot gases acting axially on the nozzle 26.

It can thus be seen that a method and apparatus have been herein provided for preventing the passage of combustion gases along the axial length of a fuel injection nozzle. It can also be seen that the method and apparatus of the present invention provide for the reduction of the area of the nozzle exposed to the high temperature cylinder gases so as to reduce the heat conduction therethrough to apparatus remote from the cylinder. Since the combustion gases are prevented from seeping along the length of the nozzle, no carbon deposits may be formed thereon so that the nozzle may be easily removed from within the retaining bore hole without carbonaceous adhering substances cementing the nozzle therein. Likewise, the ingredients and heat of the cylinder gases are prevented from directly penetrating the fuel inlet fitting and nozzle mounting apparatus so that any removable member thereof will not become frozen or seized with another member. This feature facilitates servicing of the fuel injection nozzle. Since the heat seal of the present invention completely fills the annular space between the fuel injection nozzle and the surface 18 of retaining bore hole at the combustion chamber end thereof, the high temperature gases are prevented from traveling axially of the annular space and from burning any significant portion of the surfaces of the seal 10 to reduce the efficiem cy thereof. Only a small annular radially extending surface and a short axial length of the outer surface of the seal are exposed to the burning gases which surfaces may be protected by an annular monel insulating member 43. a

The overall effects of the present invention are then: to prolong the life of a fuel injection nozzle, to create a more effective heat seal for keeping heat within the cylinder, to facilitate servicing of the fuel injection nozzle by preventing the seizing of movable parts together, and the preservation of the heat se'al itself by preventing the hot cylindergases from affecting but a very small portion of thesurfaces thereof.

While what has been described herein comprises a preferred and an alternative embodiment of the present invention, it is, of course, understood that various modifications and changes may be made therein without departing from the invention. It is therefore intended to cover in the appended claims all such modifications and changes as fall within the true spirit and scope of the present invention.

lclaim:

1. Apparatus comprising:

an internal combustion engine having at least one cylinder, including a combustion chamber;

at least a first bore hole extending from within said at least one cylinder and combustion chamber outwardly thereof;

at least a second bore hole coaxially and longitudinally outwardly extending with respect to said first bore hole,

said second bore hole having a diameter greater than the diameter of said first bore hole thereby forming a radially offset shoulder at the interface of said first bore hole with said second bore hole;

a fuel injection nozzle disposed in close proximity within said at least first and second bore holes;

an elongate annular volume adjacent to said combustion chamber being defined by said radially offset shoulder, an internal surface of said second bore hole and an external surface of said fuel injection nozzle, said annular volume adjacent to said combustion chamber having an axial length substantially greater than the radial distance between said internal surface of said second bore hole and said external surface of said fuel injection nozzle;

an elongate generally cylindrical seal member disposed about the fuel injection nozzle, said seal member having an axial length substantially greater than the radial wall thickness thereof to substantially fill, in a relaxed condition, said elongate annular volume;

said elongate generally cylindrical seal member consisting of a firm but pliable heat resistance substance;

said seal member being operably axially compressible; and

means for expanding said seal member to radially and axially completely fill said annular volume adjacent to said combustion chamber and forcing said seal member to radially abut against the surfaces defining the radial extent of said annular volume thus preventing hot combustion gases from entering said elongate annular volume.

2. An apparatus according to claim 1 wherein the axial compressive forces are provided by a nozzle mounting urging against a surface on the fuel injection nozzle.

3. Apparatus according to l with the addition of an annular disc-like insulating member disposed adjacent a hot axial end of said annular heat resistant seal member about said radially offset shoulder.

4. An apparatus according to claim 1 wherein said seal member is compressed between a generally radially extending surface on the fuel injection nozzle and said radially offset shoulder.

5. An apparatus according to claim 4 wherein said generally radially extending surface on the fuel injection nozzle is formed on a fuel inlet fitting mounted on a rear portion of the fuel injection nozzle.

6. An apparatus according to claim 3 wherein'said annular disc-like insulating member consists of monel.

7. An apparatus according to claim 3 wherein said annular disc-like member forms a space extending axially of said seal member for providing a path for extruded seal member material overflowing from said annular volume when said seal member is operatively compressed therein. 

1. Apparatus comprising: an internal combustion engine having at least one cylinder, including a combustion chamber; at least a first bore hole extending from within said at least one cylinder and combustion chamber outwardly thereof; at least a second bore hole coaxially and longitudinally outwardly extending with respect to said first bore hole, said second bore hole having a diameter greater than the diameter of said first bore hole thereby forming a radially offset shoulder at the interface of said first bore hole with said second bore hole; a fuel injection nozzle disposed in close proximity within said at least first and second bore holes; an elongate annular volume adjacent to said combustion chamber being defined by said radially offset shoulder, an internal surface of said second bore hole and an external surface of said fuel injection nozzle, said annular volume adjacent to said combustion chamber having an axial length substantially greater than the radial distance between said internal surface of said second bore hole and said external surface of said fuel injection nozzle; an elongate generally cylindrical seal member disposed about the fuel injection nozzle, said seal member having an axial length substantially greater than the radial wall thickness thereof to substantially fill, in a relaxed condition, said elongate annular volume; said elongate generally cylindrical seal member consisting of a firm but pliable heat resistance substance; said seal member being operably axially compressible; and means for expanding said seal member to radially and axially completely fill said annular volume adjacent to said combustion chamber and forcing said seal member to radially abut against the surfaces defining the radial extent of said annular volume thus preventing hot combustion gases from entering said elongate annular volume.
 2. An apparatus according to claim 1 wherein the axial compressive forces are provided by a nozzle mounting urging against a surface on the fuel injection nozzle.
 3. Apparatus according to 1 with the addition of an annular disc-like insulating member disposed adjacent a hot axial end of said annular heat resistant seal member about said radially offset shoulder.
 4. An apparatus according to claim 1 wherein said seal member is compressed between a generally radially extending surface on the fuel injection nozzle and said radially offset shoulder.
 5. An apparatus according to claim 4 wherein said generally radially extending surface on the fuel injection nozzle is formed on a fuel inlet fitting mounted on a rear portion of the fuel injection nozzle.
 6. An apparatus according to claim 3 wherein said annular disc-like insulating member consists of monel.
 7. An apparatus according to claim 3 wherein said annular disc-like member forms a space extending axially of said seal member for providing a path for extruded seal member material overflowing from said annular volume when said seal member is operatively compressed therein. 